1. Field of the Invention
The present invention relates to liquefaction of carbonaceous substances and more particularly to an improved process for liquefaction of coal.
2. Description of the Prior Art
The U.S. reserve of coal is about 3 trillion tons. Although the most abundant (80%) fossil fuel in America is coal, the U.S. consumption pattern is quite a reversal of form in terms of utilization, with coal representing only 17%, oil and gas about 78%.
The demand for all the fossil fuels combined is expected to double by the year 2000, even with increasing the use of nuclear power. While the domestic supply of crude oil and natural gas is not likely to keep pace with the energy demand, coal can play an important role in filling such a gap and thus reduce the requirements for imported supplies of oil and gas.
At the present time, about one-half of the electric power in the United States is generated from natural gas and petroleum; most of the other half is from coal. If coal can be economically converted to clean fuel for electric utilities, it could supply most of the energy needs of the United States for the next three centuries and the rapidly depleting petroleum and natural gas resources could be conserved for other essential uses, especially as a raw material for the synthetic rubber and plastics industries. Liquefied coal can also supply chemical intermediates and useful raw materials for these industries.
The methods used to liquefy coal are expensive and complex. There are other plentiful organic carbonaceous substances not presently being utilized such as cellulose waste, e.g., black liquor, heavy petroleum based materials, or sludge from waste treatment that are not presently being processed into hydrocarbon oils since efficient conversion processes have not been developed.